Flying disc

ABSTRACT

The invention relates to a flying disc constituted as a disc with a first and a second side. The second side has a central portion that is concave and the central portion is surrounded by an innermost rim ( 2 ) and an outermost rim ( 1 ) extending to the disc&#39;s periphery. The innermost rim ( 2 ) is separated from the outermost rim ( 1 ) by a circularly symmetrical depression ( 3 ). This depression gives the disc superior aero dynamical properties, allowing it to glide further in the air than corresponding prior art discs. 
     In one embodiment, the face of the outermost rim ( 1 ) nearest the centre of the disc extends essentially in parallel to the centre axis of the disc. This makes it particularly easy to grasp the disc and facilitates throwing the disc. 
     In another embodiment, the concave central portion of the second side extends along a virtual concave surface to the innermost rim, where the virtual concave surface further extends essentially to the part of the outer rim that extend the furthest from the first side of the disc. This further optimizes the aero dynamical properties of the disc. 
     Typically, the outermost rim ( 1 ) has a face on the second side of the disc, which is concave, and the first side of the disc is convex.

The present invention relates to a flying disc according to the introductory portion of the independent claim.

BACKGROUND OF THE INVENTION

Flying discs intended for sports of types similar to those call golf discs of Frisbees are known in the art. One example of such a disc is disclosed by EP2407223, showing a disc with a convex upper side and a concave lower side extending to a solid outer rim. The outer rim constitutes most of the mass of the disc and gives the disc an enhanced ability to spin while gliding through the air. A wide outer rim is however ill suited for grasping the disc, and the disc has a less than optimal ability to glide long distances.

An object of the invention is therefore to provide a flying disc with improved aero dynamical properties than with prior art discs, allowing it to fly longer distances than prior art discs.

These and other objects are attained by a flying disc according to the characterising portion of the independent claim.

SUMMARY OF THE INVENTION

The invention relates to a flying disc constituted as an essentially circularly symmetrical disc with a first and a second side. The second side has a central portion that is concave and the central portion is surrounded by an innermost rim 2 and an outermost rim 1 extending to the disc's periphery. The innermost rim 2 is separated from the outermost rim 1 by a circularly symmetrical depression 3. This depression advantageously gives the disc superior aero dynamical properties, allowing it to glide further in the air than corresponding prior art discs.

In a particularly advantageous embodiment, the face of the outermost rim 1 nearest the centre of the disc extends essentially in parallel to the centre axis of the disc. This makes it particularly easy to grasp the disc and facilitates throwing the disc.

In another advantageous embodiment, the concave central portion of the second side extends along a virtual concave surface to the innermost rim, where the virtual concave surface further extends essentially to the part of the outer rim that extend the furthest from the first side of the disc. This further optimizes the aero dynamical properties of the disc.

Typically, the outermost rim 1 has a face on the second side of the disc, which is concave, and the first side of the disc is convex.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the flying disc in partial cross section as seen from below

FIG. 2 shows the flying disc as seen from below

FIG. 3 shows a top view of the flying disc

FIG. 4 shows a cross section through the flying disc

FIG. 5 shows in greater detail part of the flying disc in cross section

DESCRIPTION OF A PREFERRED EMBODIMENT

The invention refers to a disc like object that is intended to the thrown into the air and used in a way similar to how a golf disc or Frisbee is used. The flying disc may be embodied in many different ways and still lie within the protective scope of the invention, but it is here exemplified by one embodiment only.

FIG. 1 shows the flying disc in partial cross section as seen at an angle from below, that is the figure illustrates the surfaces that while in use faces downwards. One quarter of the disc has been cut out in order to make understanding the figure easier, but in reality the disc of course looks like how it is depicted in FIG. 2.

As seen from below, the disc is a circularly symmetrical object with an outermost, circular rim 1. The lower side of the disc has a number of concentrically arranged design features that will be described in greater detail in conjunction with FIGS. 4-5. The outermost rim 1 is the design feature that extend the furthermost from the lower side of the flying disc and constitutes the part of the disc that it rests on when lying on the ground. Inside the outermost rim 1 sits an inner rim 2 and the two rims are separated by a circular depression 3. The depression 3 is what gives the flying disc its advantageous aero dynamical properties, but it also constitutes a portion of the disc where the fingers of a user may sit when grasping the disc.

The inner rim 2 does not extend a far downwards as the outermost rim 1, and the bottom surface of the disc inside the inner rim is concave.

FIG. 3 shows a top view of the flying disc, which is the part of the disc that in normal use is facing upwards. The upper side of the disc is a smooth, circularly symmetrical convex surface. This is in order to optimize its aero dynamical properties.

FIG. 4 shows a cross section through centre of the flying disc, and here the design features of the disc are more clearly illustrated. The upper side of the disc has a nearly flat central portion, with sloping outer portions that together form a slightly convex shape.

The lowermost part of the disc is constituted by the outer rim 1, and the lowermost peak of the rim define a surface 4 that the disc would be resting on if it sits on a flat surface. The outer face 5 of the outermost rim 1 is concave, and this is an adaptation intended to optimize the aero dynamical properties of the disc. The inner face of the outermost rim is however nearly cylindrical, and in the cross section shown, it extends upwards in the direction of the top surface of the disc nearly parallel to the centre axis of the disc. The inner face extends up to the bottom of the depression between the innermost 2 and outermost 1 rims.

The depression between the innermost 2 and outermost 1 rims has a bottom surface that extends nearly parallel to the top surface of the disc, and the thickness of the disc is here small as compared to the thickness of the rims. In particular, the outermost rim constitutes a large portion of the total weight of the disc, giving the disc a small total weight while still giving the disc a maximized ability to continue to rotate on its own when it has been set in motion.

The innermost rim 2 has an outer face that constitutes the inner side of the depression and it also falls steeply into the depression 3. The inner face of the innermost rim does instead constitute part of a smooth, concave surface that extends all the way to the centre of the lower side of the disc. Over most of the central portion of the disc, the thickness of the disc is small as compared to the rims, making the total weight of the disc low. This central portion of the disc is concave and smoothly changes direction further and further downwards as it nears the innermost rim 2, and when it ends at the top of the innermost rim, that is where the innermost rim reaches the furthers downwards in the figure, the central portion is directed towards the top of the outermost rim 1. This means that if the central portion of the lower surface of the disc had been extrapolated further outwards towards the outer rim, the whole lower surface of the disc would constitute one continuous convex surface, interrupted only by the depression 3 between the outermost and innermost rims, only to change character at the outer face of the outermost rim 1.

The depression 3 is what gives the disc its attractive aerodynamic properties, allowing it to fly further than similar discs without this depression. It is also advantageous that the inner portion of the lower side of the disc is designed the way it is in this embodiment, further enhancing its advantageous aero dynamical properties, but this does not necessarily have to be the case. Other embodiments with differently shaped depression have also been shown to have advantageous aero dynamical properties, and obviously all these versions are also intended to sit within the protective scope of the invention.

FIG. 5 shows in greater detail the outer part of the flying disc in cross section. Here, the convex shape of the outer face 5 of the outermost rim 1 is more clearly shown. This convex property gives the disc lift as it flies through the air, but the outer face may also be what in this cross section would be shown as flat or even concave. The inner face of the outermost rim is in cross section illustrated as extending almost straight upwards and is nearly flat, that is it constitutes a near cylindrical surface. A user that tries to grasp the disc would therefore very conveniently extend fingers into the depression and grasp the disc by placing a thumb on the top surface of the disc, giving a very firm grip indeed. This firm grip allows the user to more easily throw the disc at a high speed and give it a high rotational speed.

The reason the depression 3 in the disc gives it its advantageous aero dynamical properties can most easily be described in that when a normal disc is thrown, the free stream air is divided in two distinct flows right at the disc's leading edge. The upper side of disc is relatively streamlined and with a relatively low drag. The bottom side of the disc, however, does have a cylindrical cavity nearly as deep as the total height of the disc. The geometry of this cavity provokes the flow diverted at the leading edge towards the bottom of the disc to separate from the disc surface, creating a highly turbulent flow close to the rim which extends towards the back of the disc. Even at zero degrees angle of attack, part of the free stream flow passing below the disc tend enter that cavity and as the disc flies it collides against the cavity wall in the rear part of it, generating drag and further turbulences.

A disc with a depression on the lower side provides a more streamlined geometry in the lower side of the disc which significantly reduces the overall induced drag. That is mainly due to the fact that a smaller portion of the flow in the underside of the disc collides against the rear part of the cavity which is a ridge. Most of the flow diverted by the disc nose towards the bottom still separates when it encounters the ridge but it is also true that a large part of it re-connects with the disc surface thanks to the depression. A portion of the flow remains in the ridge but it stays significantly more stationary. Moreover, at the rear part of the disc the flow separates, again, at the ridge which causes a highly localized turbulent flow within the ridge but its extensions is much smaller compared with the conventional discs without depression, and rather confined.

Although the invention has been described in conjunction with a preferred embodiment, it is to be understood that various modifications may still be made without departing from the scope of the invention as defined by the appended claims. Several such modifications have been presented in the description above, but obviously others are also conceivable. 

1. A flying disc constituted as an essentially circularly symmetrical disc with a first and a second side, where the second side has a central portion that is concave and where the central portion is surrounded by an innermost rim (2) and an outermost rim (1) extending to the disc's periphery, characterised in that the innermost rim (2) is separated from the outermost rim (1) by a circularly symmetrical depression (3).
 2. A flying disc according to claim 1, characterised in that the face of the outermost rim (1) nearest the centre of the disc extends essentially in parallel to the centre axis of the disc.
 3. A flying disc according to claim 1, characterised in that the concave central portion of the second side extends along a virtual concave surface to the innermost rim, where the virtual concave surface further extends essentially to the part of the outer rim that extend the furthest from the first side of the disc. 